(a) Technical Field
The present invention relates to a separator assembly to be disposed in a fuel cell that structurally improves structural safety and the durability of a fuel cell stack and allows for mass-production of fuel cell stacks, and a method of manufacturing the same.
(b) Background Art
In general, fuel cells generate electric power by directly converting chemical energy generated by oxidation of a fuel into electric energy, and directly supply hydrogen produced by modifying or purifying a hydrocarbon-based fuel or a hydrocarbon-based fuel and air into a fuel cell stack to allow fuel and air to generate an electrochemical reaction and thus generate electrical energy.
In a fuel cell stack, a plurality of membrane-electrode assemblies (MEAs), each including an anode, a cathode, and an electrolyte membrane interposed between the anode and the cathode. A plurality of unit cells, each include separators for separating the membrane-electrode assembly, are stacked together to form a fuel cell stack.
Fuel cell stack separators may conventionally include graphite separators and metal separators. The manufacturing time and costs of the metal separators, however, are significantly reduced compared to graphite separators manufactured through machining or powdering. Since these separators are made of metal, the separators must be made thin in order to reduce the weight of the fuel cell stacks.
As a result, however, these metal separators have low strength and increase in their spring back as the thickness of the material decreases. This causes deterioration in the alignment of the stacks and an increase in error rates of the metal separators that influence mass-production of the stacks.
In a fuel cell stack in which a plurality of unit cells are stacked, an alignment error between adjacent unit cells and an alignment error between adjacent separators may occur. As such, it becomes more difficult to uniformly stack a separator, an MEA, and a GDL (gas dispersing layer) due to lack of strength and an increase of a spring back as the separator becomes thinner, and a possibility of generating an alignment error between adjacent separators that influences a structure and a performance of the stack.
Further, the fuel cell stacks require reaction gases (hydrogen and air) and cooling water to be sealed therein, and are provided on opposite surfaces of a metal separator. As such, fuel cell stacks are typically integrally injection-molded in a metal separator. However, as the metal separator becomes thinner, the quality of metal separator decreases. For example, deformation of a separator or generation of a gasket burr due to an injection-molding pressure may occur, and thus an error rate of the metal separators increases.